Local degraded area repair and restoration component for pressure retaining items

ABSTRACT

What is new in the art to which my invention pertains is that it allows for a repair or restoration of a pressure retaining item that has local material degradation to an acceptable state of condition for continued operation without the need to cut out the degraded section of material or breach the pressure boundary of a pressure retaining item. Common methods of repair include removal of degraded or affected material section and replacement with a new section of equivalent material by joining the new material to an existing item at a location of adequate thickness using full or complete penetration welds. This type of repair may be referred to in the industry as a “flush patch repair”. An additional type of repair where a section of material degradation may be localized is a “weld build-up repair” wherein weld metal is deposited onto the existing area of affected material to return the material to its original thickness. Both “flush patch repair” and weld build-up repair” methods require breaching of the pressure boundary integrity of a pressure retaining item to implement a repair. The invention does not require breaching a pressure boundary.

[0001] This application claims the benefit of application Ser. No.60/275,949, Filing date Mar. 16, 2001. This application is for acomponent that is used to repair or restore structural and pressureretention integrity of pressure retaining items. Pressure retainingitems include but are not limited to items referred to as pressurevessels, tanks, towers, boilers, reactors, heat exchangers, pipe, pumps,and valves. Pressure retaining items are generally constructed ofmetallic material. Methods of construction of pressure retaining itemsincluded welded construction, bolted construction, riveted construction,and a completed pressure retaining item may be constructed using one orvarious combinations of welded, bolted, or riveted construction. Variousindustry Codes and Standards provide construction, operation, andinspection requirements pertaining to pressure retaining items in theUnited States. These include Codes and Standards published by variousorganizations including but not limited to the American Society ofMechanical Engineers (ASME), American National Standards Institute(ANSI), Tubular Exchanger Manufacturers Association (TEMA), AmericanPetroleum Institute (API), and National Board Inspection Code (NBIC).Local jurisdictional authorities (State, Commonwealth, or City) mayrequire compliance with an industry Code or Standard or a combination ofCodes and Standards. Pressure retaining items contain fluids (gases orliquids) under a pressure that may be either internal (a pressure actingon the inside of a pressure retaining item) or external (pressure actingon the outside of a pressure retaining item). Pressure retaining itemsare used to contain, move or process various fluids. Commercial andgovernment industries using pressure retaining items include but are notlimited to chemical, petrochemical, process, food, pharmaceutical,water, oil, gas industries, electrical power generation (fossil, hydro,and nuclear), government energy and nuclear process facilities, andvarious manufacturing industries.

BACKGROUND OF THE INVENTION

[0002] Pressure retaining parts of pressure retaining items may besubjected to material degradation (where degradation is defined as achange in state from that originally intended to the extend that an itemthat is identified as degraded is not capable of meeting one or moreintended purposes). Degradation of material may include thinning of amaterial, cracks forming within or upon the surface of a material,pitting of a material, or general overall structural damage in amaterial. Degradation of a material, including material thinning,pitting or cracking, may be caused by but is not limited to erosion orcorrosion. Material degradation can occur from a chemical reactionbetween the fluid contained by a pressure retaining item and itsmaterial of construction. Material degradation can occur due to movementor impingement of fluid against pressure retaining material ofconstruction of a pressure retaining item. Corrosion, erosion or othermechanisms, either individually or in combination, can result indegradation of material that is required to maintain the structural andpressure retaining capability of pressure retaining items. Degradationof a material, including material geometrical changes or changes in amaterial physical property including but not limited to changes inmaterial yield strength, tensile strength, modulus of elasticity, etc.,may be caused by an imposed load, pressure, or temperature condition.Material degradation can be global (by global it is meant thatessentially all or a large portion of the materials of construction of apressure retaining item are subjected to material degradation).Alternatively, material degradation can be local (by local it is meantthat a small amount of the total materials of construction of a pressureretaining item subjected to material degradation). Either global orlocalized material degradation can result in a potential hazardousoperating condition wherein as-designed and constructed safety factorsagainst fluid leakage or pressure retaining item structural integrity orpressure retaining item pressure boundary pressure retention capabilityare reduced. In severe material degradation conditions (either global orlocal), failure of pressure retaining items can occur. Pressureretaining item failure can result in affecting the safety of personnelsafety and/or in economic losses.

[0003] To obtain information pertaining to material degradationoccurring in pressure retaining items period inspections of pressureretaining items are performed. Inspection methods include visualinspection for observation of material degradation or visual inspectionfor observation of fluid leakage. Inspection methods also includepressure retaining item material of construction thickness measurementsfor determination of material degradation. Thickness measurements can beobtained using various data collection and nondestructive examinationmethods including but not limited to physical measurements using variousgages or measuring instruments or by performing ultrasonic examinationto obtain material condition and thickness information.

[0004] Where material degradation is determined, assessments ofremaining life and adequacy of pressure retaining item to remain inservice while continuing to operate within the requisite factors ofsafety are performed. Where it is determined that a specific pressureretaining item does not have the requisite factor of safety to continueoperation several options are available including 1) changing theconditions under which that specific pressure retaining item is operatedto conditions that are acceptable for continued safe operation, of 2)perform replacing or repairing unacceptable parts of pressure retainingitems.

[0005] Common methods of repair include removal of a material sectiondetermined to be unacceptable and replacement with a new section ofmaterial of equivalent or better structural, pressure retaining, and/orcorrosion and/or erosion resistance than that used in the originalconstruction. New sections of replacement material are most ofteninstalled by joining them to an existing pressure retaining item atlocations with adequate material thickness for continued operation ofthe item using full or complete penetration welds. This type of repairmay be referred to as a “flush patch repair”.

[0006] A different type of repair used where a section of materialdegradation may be localized is referred to as “weld build-up repair”. A“weld build-up repair” is a repair method wherein weld metal isdeposited on to the area of unacceptable material to return the materialto a condition wherein the pressure retaining item can be returned toservice under a specific set of operating conditions.

[0007] An often considered by not generally allowed by some Codes orStandards that govern the construction, operation, and inspection ofpressure retaining items, or that may not be allowed a jurisdictionalauthorities (State, Commonwealth, or City) is a method of repairreferred to as a “fillet welded patch plate” repair. In this typerepair, a section of new material is fit over a local area of a specificpressure retaining item at the location of unacceptable material andjoined to the surface of that specific pressure retaining item using afillet weld. This method of repair does not readily allow for volumetricexamination or pressure integrity examination of the completed filletweld joint and the completed repair may result in a smaller factor ofsafety than either a “flush patch repair” or “weld build-up” repair”.

[0008] “Flush patch repair” and the “weld build-up repair” methods ofrepair or restoration are generally allowed by governing Codes andStandards for construction, operation, or inspection, and are alsogenerally allowed by most jurisdictional authorities (StateCommonwealth, or City) in the United States. “Flush patch repair” andthe “weld build-up repair” methods of repair allow for a volumetricexamination and pressure integrity examination of the welds used in acompleted repair. “Flush patch repair” and the “weld build-up repair”methods may result in equal or greater pressure retention and structuralintegrity factors of safety to those that existed at the time oforiginal construction. “Flush patch repair” or “weld build-up repair”methods for repair of pressure retaining items have several limitationsor negative aspects including but not limited to:

[0009] “Flush patch repair or” “weld build-up repair”:

[0010] 1. require removal of pressure retaining items from service

[0011] 2. require cutting out of pressure retaining item local materialdegraded areas (“flush patch repair” only)

[0012] 3. require preparation of pressure retaining item remainingmaterial for welding of the new replacement section of material or weldbuildup by cutting or grinding.

[0013] 4. require exact cutting, curvature fabrication (by rolling,forming, or machining) and weld end preparation of the new section ofmaterial for fit-up (“flush patch repair” only).

[0014] 5. may require use of weld joint backing strips. The backingstrips may or may have to remain in place depending on theiraccessibility after welding. If left in place they may contribute to areduction in a pressure retaining item factor of safety or even worsethe acceleration of new local areas of corrosion or erosion due to theintroduction of a new fluid flow path obstruction (“flush patch repair”only).

[0015] 6. may expose personnel to lethal or hazardous fluid contents ofa pressure retaining item such as chemical, gas, or radioactive fluidcontents.

[0016] 7. introduce the potential for damage to internal parts ofpressure retaining items such as damage to tubes of heat exchangers.

[0017] 8. introduce the potential for intrusion of foreign materialsinto the internals of pressure retaining items.

[0018] 9. may require hydrostatic or pneumatic testing of a. pressureretaining item to insure pressure retaining integrity has beenmaintained due to breach of pressure boundary.

[0019] 10. may only be allowed on the inside surface of a pressureretaining item or may only be allowed on the outside surface of apressure retaining item depending on governing code or jurisdictionalauthority requirements.

BRIEF SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE INVENTION

[0020] The “Local Degraded Area Repair and Restoration Component forPressure Retaining Items”, hereinafter referred to as “the invention”,is a component used to repair and restore the structural and pressureretaining integrity of pressure retaining items whose pressure retainingmaterial of construction has been subjected to material degradation. Theinvention consists of a single component of metallic material that iswelded to the surface of a pressure retaining item. The invention iswelded directly over a section of material of a pressure retaining itemwhere a section of pressure retaining material has been subjected todegradation. The configuration of the invention is a single piece ofmental that has a cavity on one side built into it. The cavity portionof the invention allows for the invention having a skirt of materialcompletely around its periphery that extends below the inner facesurface of the invention. The invention can best be described by acomparison to one or more common items. To describe the invention insimple terms would be for one to compare its possible geometricconfigurations to those of 1) a standard shoe box cover, 2) the lid of ajar, 3) or an open sardine can. These are only illustrative examples forsimple comparison to the general geometric configuration of theinvention. The invention can be constructed by bending, welding,machining, forming, forging, or casting a piece of metal to match acontour of a surface of a pressure retaining item.

[0021] The end of the extended skirt portion of the invention is thenwelded to a pressure retaining item surface. This results in acompletely enclosed cavity that would be formed between a pressureretaining item surface and the inner surface of the invention. Thus asection of unacceptable pressure retaining item material is completelyencapsulated by the invention. If a section of unacceptable pressureretaining item material that is encapsulated by the invention degradesfurther, the invention assure that there would be no loss of pressureretaining or structural integrity a specific pressure retaining item towhich the invention is attached. The invention, based on an appropriatedesign and material selection that sizes the invention and itsattachment welds appropriately for the intended purpose, can provide forassurance that a pressure retaining item to which the invention isattached, has, after attachment of the invention, an original or betterfactor of safety against leakage or failure and with equal or bettercorrosion/erosion resistance, allowance, or capability than that in theas-designed and as-constructed condition of a pressure retaining item.The weld joining the invention to a pressure retaining item can be acomplete or full penetration weld whose final as-welded configurationwould allow for a complete through wall volumetric examination of theweld. Additionally, where desired, the encapsulated cavity between apressure retaining item surface and the invention could be internallypressurized within the remaining structural and pressure integritycapability of the encapsulated section of material of a pressureretaining item for further assurance of leak tightness, structuralintegrity, and pressure retaining integrity verification of a pressureretaining item and the invention after completion of attachment of theinvention.

OBJECTIVE AND ADVANTAGES OF THE INVENTION

[0022] The objective of the invention is to provide a simple, safe, costeffective, method of repairing a pressure retaining item. A furtherobjective is to provide a method of repair that alleviates or eliminatesmany, if not all, of the negative aspects of some current repairmethods, including repair methods referred to as the “flush patchrepair” or the “weld build-up repair” methods (the “flush patch repair”or the “weld build-up repair” methods are described in the previoussection of this Specification entitled “BACKGROUND OF THE INVENTION”).

[0023] It is believed that the invention alleviates many of the negativeaspects of the “flush patch repair” or “weld build-up repair” currentcommon methods of repair, and offers several advantages. Negativeaspects of the “flush patch repair” or “weld build-up repair” methods ofrepair that are alleviated by the invention and several advantages ofthe invention over the “flush patch repair” or “weld build-up repair”include but are not limited to the following:

[0024] The invention:

[0025] 1. by it use and attachment may not require removal of thepressure retaining item from service

[0026] 2. by it use and attachment may not require cutting out of thepressure retaining item local material degraded areas

[0027] 3. by it use and attachment may only require minimal preparationof the pressure retaining item material for weld attachment of theinvention in comparison to the “flush patch repair” or the “weldbuild-up repair” methods.

[0028] 4. by it use and attachment may eliminate or minimize use of weldjoint backing strips in the attachment weld between a pressure retainingitem and the invention which then by not using said weld joint backingstrip would substantially reduce or eliminate in most cases arequirement to impose or consider a reduction in the pressure retainingitem factor of safety as applicable to a pressure retaining item'spressure retention or structural integrity.

[0029] 5. by it use and attachment may eliminate or minimize use of weldjoint backing strips in the attachment weld between a pressure retainingitem and the invention which then by not using said weld joint backingstrip would substantially reduce or eliminate an attachment with ageometrical configuration that would contribute to acceleration ofexisting areas of erosion or corrosion or lead to new areas that wouldbe subjected to erosion or corrosion at rates in excess of those thatexisted prior to the attachment of the invention.

[0030] 6. by it use and attachment may eliminate exposure of personnelto lethal or hazardous fluid contents such as chemical, gas, orradioactive fluid contents of a pressure retaining item.

[0031] 7. by it use and attachment may eliminate the potential fordamage to internal parts of pressure retaining items such as damage totubes of heat exchangers. Damage to tubes of heat exchangers wouldnecessitate repair of tubes or plugging of tubes with an associated lossin equipment performance and economic loss.

[0032] 8. by it use and attachment may eliminates the potential forintrusion of foreign materials into the internals of pressure retainingitems.

[0033] 9. by it use and attachment may simplifies any requiredhydrostatic or pneumatic testing of pressure retaining item to insurepressure retaining integrity has been maintained due to breach ofpressure boundary.

[0034] 10. is not limited to a specific geometrical shape. It may beconstructed to most any regular or irregular shape including but notlimited to round, square, rectangular, obround, oval, triangular, or anycombination of the these shapes.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0035] General

[0036] There are two drawings that describe the invention, Drawing Sheet1/2 and Drawing Sheet 2/2. Drawing Sheet 1/2 provides a generalarrangement and general details of a geometrically round local degradedarea repair and restoration component. Drawing Sheet 2/2 provides ageneral arrangement and general details of a geometrically obround localdegraded area repair and restoration component. The invention, however,is not limited to shape. It may be constructed to most any regular orirregular shape including but not limited to round, square, rectangular,obround, oval, triangular, or any combination of the these shapes. Twodrawings, Drawing Sheet 1/2 and Drawing Sheet 2/2 are provided todescribe the general concept of the invention but these two drawings donot describe all possible detailed configurations or geometrical shapesof the invention.

[0037] Drawing Sheet 1/2—Plan View

[0038] The plan view shows how the invention would appear if one were toview a surface of a pressure retaining item after the invention had beenattached. The surface of a pressure retain item could be, as anexample: 1) a surface of a cylindrical pressure vessel shell, 2) asurface of a pressure vessel end closure head, 3) a surface of a pipe,4) a surface of a shell of a flat bottomed storage tank, 5) a compoundcurved surface of a pump body, or 6) a compound curved surface of avalve body, amongst other pressure retaining item surfaces to which theinvention can be attached. The irregular solid line depicts the boundaryof a small section of a pressure retaining item surface that is beingshown in the view. The outer solid circular line identified as the LocalDegraded Area Repair and Restoration Component is the periphery of theinvention. The two (2) inner dotted circular lines depict the inner wallof the invention's skirt (outer dotted Line), and the juncture of thecavity cut radius to cavity flat portion cut out bottom [see Detail Afor more information on what these two dotted lines show]. It should benoted that in some specific invention design geometrical configurationsthe depth of the cavity and the cavity cut radius could be the same. Inthese instances based on common drafting and detailing practices thisinner dotted line would not be shown. The cross hatched area in thecenter of the invention with the irregular boundary represents thatlocal area of pressure retaining item material's surface where materialdegradation has occurred. The upper left hand corner depicts a sampleweld joint connection configuration of the invention to a pressureretaining item. It details a complete or full penetration weldsupplemented by a fillet weld with this fillet weld size beingspecifically dependent on a pressure loading and geometry of a specificpressure retaining item, a Code or Standard (a Code or Standard isdescribed in the section of this Specification entitled “BACKGROUND OFTHE INVENTION”), and the invention size, shape, and geometry.

[0039] Drawing Sheet 1/2—View A-A

[0040] View A-A shows how the invention would look if one were to cutthrough the center of the invention after it being attached to apressure retaining item. A local area of pressure retaining itemmaterial degradation can be seen. Also note that this view presents theinvention as welded to a cylindrical surface. This is only an example ofthe geometry of surface to which the invention can be applied.

[0041] Drawing Sheet 1/2—Detail “A”

[0042] This detail shows the basic configuration of the cavity and skirtof the invention. A description of a weld preparation detail is shown,as are various material thickness and dimensions, including any requiredcurved sections of the invention required to match the contour or thesurface of a pressure retaining item to which the invention is beingattached.

[0043] It should also be noted that this detail is also associated withDrawing Sheet 2/2 and is referred to in “SECTION B-B OR C-C” of thatdrawing.

[0044] Drawing Sheet 2/2—Plan View

[0045] The plan view shows how the invention would appear if one were toview the outer surface of a pressure retaining item after the inventionhad been attached to a pressure retaining item surface. The surface of apressure retain item could be, as an example: 1) a surface of acylindrical pressure vessel shell, 2) a surface of a pressure vessel endclosure head, 3) a surface of a pipe, 4) a surface of a shell of a flatbottomed storage tank, 5) a compound curved surface of a pump body, or6) a compound curved surface of a valve body, amongst other pressureretaining item surfaces to which the invention can be attached. Theirregular solid line depicts the boundary of the small section of thepressure retaining item surface that is being shown in the view. Theouter solid circular line identified as the Local Degraded Area Repairand Restoration Component is the periphery of the invention. The innerdotted circular line depicts the inner wall of the invention's skirt[see Detail 1 on Drawing Sheet 1/2 for more information on the innerskirt wall that this dotted line represents]. The cross hatched area inthe center of the invention with the irregular boundary represents thatlocal area of pressure retaining item material where materialdegradation exists. The lower right hand corner of the PLAN depicts asample weld joint connection configuration of the invention to apressure retaining item. It details a complete or full penetration weldsupplemented by a fillet weld with this fillet weld size beingspecifically dependent on a pressure loading and geometry of a specificpressure retaining item, a Code or Standard (a Code or Standard isdescribed in the section of this Specification entitled “BACKGROUND OFTHE INVENTION”), and the invention size, shape, and geometry

[0046] Drawing Sheet 1/2—View B-B or C-C

[0047] View B-B or C-C shows how the invention would look if one were tocut through the center of the invention in either of two directions(long direction view) or short direction view) after the invention beingwelded to a pressure retaining item. The local area of pressureretaining item material degradation can be seen. Also note that thisview presents the invention as welded to a cylindrical surface. This isonly an example of the geometry of surface to which the invention can beapplied.

[0048] Drawing Sheet 2/2—Detail “B”

[0049] This detail shows the basic configuration of how the end of anobround shaped invention would look at the juncture of the long side ofthe invention to the rounded ends of the invention (this is shown as thesolid line). Additionally, this detail shows the basic configuration ofhow the end of an obround shaped invention would look at the juncture ofthe skirt inside long side of the invention to the inside skirt roundedends of the invention (this is shown as the dotted line).

DETAILED DESCRIPTION OF THE INVENTION

[0050] General

[0051] The “Local Degraded Area Repair and Restoration Component forPressure Retaining Items”, hereinafter referred to as “the invention”,is a component used to repair and restore the structural and pressureretaining integrity of pressure retaining items whose pressure retainingmaterial of construction has been subjected to material degradation. Theinvention consists of a single component of metallic material that iswelded to the surface of a pressure retaining item. The invention iswelded directly over a section of the pressure retaining item wherematerial degradation has occurred. Installation of the invention on apressure retaining item can return the structural and pressure retainingintegrity, and allowance for corrosion and/or erosion of a pressureretaining item to equal or better conditions than the originalas-designed or as-constructed condition of the pressure retaining item.

[0052] Construction of Invention

[0053] The invention is shown in sample invention Drawing Sheet 1/2(sample drawing of a round shape invention) and Drawing Sheet 2/2(sample drawing of an obround shape invention). The invention can be ofany shape including but not limited to round, square, rectangular,obround, oval, triangular, or any combination of the these shapes.

[0054] The configuration of the invention is a single piece of metalthat has a cavity on one side built into it. The cavity portion of theinvention allows for the invention having a skirt of material completelyaround its periphery that extends below the inner face surface of theinvention. The invention can best be described by a comparison to one ormore common items. To describe the invention in simple terms would befor one to compare its possible geometric configurations to those of 1)a standard shoe box cover, 2) the lid of a jar, 3) or an open sardinecan. These are only illustrative examples for simple comparison to thegeneral geometric configuration of the invention. The invention can beconstructed by bending, welding, machining, forming, forging, or castinga piece of metal to match a contour of a surface of a pressure retainingitem.

[0055] The invention can be manufactured or fabricated from a singlepiece of metal plate, forging, or casting, or can be fabricated using acombination of metal plate, forging, or casting parts by welding thesepieces together to make the invention. Curved areas of the invention maybe made by rolling the invention in a set of plate rollers to thedesired curvature. During this rolling process the cavity of theinvention may be filled with a piece of metal plate to prevent damage ofthe weld end portion of the invention skirt. For inventions of verythick parts, the invention may be heated before the rolling process tofacilitate the fabrication process. Curved areas of the invention may bemade by machining of parts to achieve the desired curvatures. Theinvention may be manufactured by the casting process wherein all partsincluding the curved parts of the invention are achieved during thecasting process. A forming process wherein the configuration of theinvention is arrived at by using a die and forming process may be usedto manufacture the invention.

[0056] The final process of manufacture may consist of machining andgrinding to arrive at the final configuration.

[0057] Drawing Elements

[0058] The flat plate surface or face of the invention can have a duelfunction. Where the invention is attached to the surface of a pressureretaining item where said surface is the opposite side surface to whicha pressure or fluid acting to create erosion or corrosion, the inventioncan provides a barrier against pressure loss of the pressure integrityloss of the pressure retaining item and/or a barrier to prevent ormaintain within acceptable limits erosion or corrosion of the surface towhich erosion or corrosion is acting. Should the degraded materialsection of a pressure retaining item be breached or leak the inventionmaintains pressure integrity of a pressure retaining item. Additionallythe invention maintains structural integrity of a pressure retainingitem by its being designed to provide the requisite structural integrityof a pressure retaining item. The skirt which runs around the peripheryof the invention maintains pressure integrity and structural integrityof a pressure retaining item by its being designed to provide therequisite structural integrity of the pressure retaining item andtransfer of loading from pressure retaining item material adjacent tothe attached invention into and then through the invention back into apressure retaining item. The flat plate and skirt parts of the inventioncan be designed such that they substantially reduce or eliminateentirely the necessity for the degraded material section to eithertransfer any load or maintain provide load bearing capability assistancein the maintenance of structural integrity of a pressure retaining item.The cavity of the invention allows for the invention to be complete orfull penetration weld joined at the skirt end to a pressure retainingitem. This type of complete or full penetration weld allows for acomplete volumetric examination of a weld to be performed to insurestructural integrity of a weld joint of this type weld joint attachment.Additionally, depending on the remaining strength of degraded materialencapsulated by the invention the cavity of the invention can bepressurized for leak tightness and structural integrity testing. Thefabrication of curved surfaces allows for mating of the invention to thesurface of a pressure retaining item. All machined radius of theinvention can be designed to a size required to reduce stressconcentrations during operation of a pressure retaining item with theinvention installed. The weld between the invention and the pressureretaining item is generally full or complete penetration supplemented bya fillet weld. Fillet welds supplementing full penetration weldsattaching the invention to a pressure retaining item can be sized forthe requisite load capacity, structural integrity, and pressureintegrity. Fillet welds can be sized to comply with requirements thatmay apply to fillet welds supplementing full penetration welds or tofillet welds in general as required by any Code or Standard beingimposed by jurisdictional authorities or governing the overall designand construction of the invention.

[0059] Value and Improvement of Invention over Current Repair Methods

[0060] The invention offers several improvements and areas of increasedvalue over current methods of repairing eroded/corroded or degradedsections of pressure retaining items. The invention resolves manynegative aspects of the “flush patch repair” or “weld build-up repair”current common methods of repair, and offers several advantages. Thefollowing includes several of these values and improvements:

[0061] 1. Removal of pressure retaining item from service

[0062] “flush patch repair”—required

[0063] “weld build-up repair”—required

[0064] Invention—may not be required in all cases

[0065] 2. Cutting out of pressure retaining item local material degradedareas

[0066] “flush patch repair”—required

[0067] “weld build-up repair”—not required

[0068] Invention—not required

[0069] 3. Preparation of pressure retaining item material for weldingduring repair method

[0070] “flush patch repair”—required

[0071] “weld build-up repair”—required

[0072] Invention—may not be required or minimal if required

[0073] 4. Installation of weld joint backing strips (Backing strips cancause a reduction in the pressure retaining item factor of safety oreven worse the acceleration of new local areas of corrosion or erosion)

[0074] “flush patch repair”—may be required

[0075] “weld build-up repair”—not required

[0076] Invention—not required

[0077] 5. Potential exposure of personnel to lethal or hazardous fluidcontents such as chemical, gas, or radioactive fluid contents of thepressure retaining item

[0078] “flush patch repair”—yes

[0079] “weld build-up repair”—yes

[0080] Invention—no

[0081] 6. Potential for damage to internal parts of pressure retainingitems such as damage to tubes of heat exchangers. Damage to tubes ofheat exchangers may necessitate repair or plugging of the tubes with anassociated loss in equipment performance and economic loss or tubereplacement with associated economic cost.

[0082] “flush patch repair”—yes

[0083] “weld build-up repair”—yes

[0084] Invention—no

[0085] 7. Potential for intrusion of foreign materials into theinternals of pressure retaining items.

[0086] “flush patch repair”—yes

[0087] “weld build-up repair”—yes

[0088] Invention—generally no

[0089] 8. Hydrostatic or pneumatic testing of pressure retaining itemafter repair to insure pressure retaining integrity has been maintaineddue to breach of pressure boundary

[0090] “flush patch repair”—generally required

[0091] “weld build-up repair”—generally required

[0092] Invention—not generally required

[0093] 9. Improved structural and pressure retaining integrity ofpressure retaining item at location of material degradation

[0094] “flush patch repair”—possible

[0095] “weld build-up repair”—generally not possible

[0096] Invention—generally yes

[0097] 10. Improved corrosion/erosion allowance of pressure retainingitem at location of material degradation

[0098] “flush patch repair”—possible

[0099] “weld build-up repair”—generally not possible

[0100] Invention—generally yes

[0101] 11. Repair Hardware Cost

[0102] “flush patch repair”—generally lower than invention

[0103] “weld build-up repair”—lowest

[0104] Invention—generally highest

[0105] 12. Installation Cost

[0106] “flush patch repair”—generally higher than invention

[0107] “weld build-up repair”—generally higher that invention

[0108] Invention—generally lowest

[0109] 13. Economic Cost Due to Facility/Process Downtime

[0110] “flush patch repair”—generally much higher than invention

[0111] “weld build-up repair”—generally much higher than invention

[0112] Invention—generally very low

[0113] 14. Personnel Environmental (Lethal Fluid/Radiation) ExposureRisk

[0114] “flush patch repair”—generally much higher than invention

[0115] “weld build-up repair”—generally much higher than invention

[0116] Invention—generally eliminated

[0117] 15. Degraded Material Disposal Cost Due

[0118] “flush patch repair”—higher than invention

[0119] “weld build-up repair”—very low, possibly none

[0120] Invention—none

[0121] An additional positive aspect of the invention is that if thesection of degraded material of a pressure retaining item, where saidmaterial is encapsulated by the invention, continues to further degradeafter attachment of the invention, such that the pressure retentionintegrity of the pressure retaining item at said material location isbreached, then:

[0122] the invention can provide for complete retention of the pressureretaining item's pressure integrity and with the original or betterfactor of safety against leakage or failure and with equal or bettercorrosion/erosion allowance or capability based on the inventionsthickness and/or material of construction.

[0123] In most cases, but not all, the attachment weld joining theinvention to a pressure retaining item would be a complete or fullpenetration weld whose final as-welded configuration allows for acomplete through wall volumetric examination of the weld to be performed(generally by ultrasonic examination). Additionally, where desired, thecavity between a pressure retaining item surface and the invention canbe internally pressurized within the remaining structural and pressureintegrity capability of an encapsulated section of material of apressure retaining item for further leak tightness assurance.

What I claim as my invention is:
 1. the inventions is a one piececomponent that can be integrally attached to the surface of a pressureretaining item for the purpose of repair or restoration or enhancementof the pressure retaining item's capability in one or a combination thefollowings areas: pressure retention capability, structural integritycapability, corrosion resistance capability, or erosion resistance by:encapsulating a section of a pressure retaining item material thatwithin that section of material being encapsulated exists a degradedarea of material that is of a condition that is not acceptable. Apressure retaining item section of material may be unacceptable becausethe material is thinner, or contains pitting, or contains cracks suchthat the material differs from a condition of: as-designed; or,as-constructed; or, as-required for a requisite loading condition; or,as required to resist a requisite corrosion allowance for a specifictime period of operational service under specific conditions ofoperation: or, as required to provide a requisite erosion allowance fora specific time period of continued operation.